Device for positioning stock in a printing mechanism

ABSTRACT

A device for accurately positioning stock in a printing mechanism is described. The labels are printed on a rolled stock of paper which travels past the printing mechanism. It therefore is necessary to accurately stop the linear motion of the paper so that the area of the paper where printing is to take place is properly positioned with respect to the printing mechanism. The invention achieves this result. The invention includes an element for sensing the edges of the labels upon which printing takes place. The sensing element slides along the rolled stock as the stock travels toward the printing mechanism. Because of the configuration of the sensing element, contact with the edge of the label causes the sensing element to rotate. An opaque element is fixedly coupled to the sensing element. During sliding the opaque element prevents light from a source from impinging upon a photodetector. Rotation of the sensing element momentarily displaces the opaque element, thereby permitting light to fall upon the photodetector, thus producing an output signal which is utilized to stop movement of the paper until a printing operation is completed.

United States Patent 1191 Moss [11] 3,889,111 [451 June 10, 1975 1DEVICE FOR POSITIONING STOCK IN A PRINTING MECHANISM [75] Inventor:James R. Moss, Mt. Clemens, Mich.

[73] Assignee: The Bendix Corporation, Southfield,

Mich.

22 Filed: Dec. 26, 1973 21 Appl. NO.Z 427,884

[52] US. Cl 250/237 R; 226/45; 250/548; 250/561 [51] Int. Cl. HOlj 5/16[58] Field of Search 250/548, 561, 222 PC, 223, 250/237; 226/45, 30

Primary Examiner-James W. Lawrence Assistant Examiner-D. C. NelmsAttorney, Agent, or Firm-Lester L. Hallacher [57] ABSTRACT A device foraccurately positioning stock in a printing mechanism is described. Thelabels are printed on :1 rolled stock of paper which travels past theprinting mechanism. It therefore is necessary to accurately stop thelinear motion of the paper so that the area of the paper where printingis to take place is properly positioned with respect to the printingmechanism. The invention achieves this result. The invention includes anelement for sensing the edges of the labels upon which printing takesplace. The sensing element slides along the rolled stock as the stocktravels toward the printing mechanism. Because of the configuration ofthe sensing element, contact with the edge of the label causes thesensing element to rotate. An opaque element is fixedly coupled to thesensing element. During sliding the opaque element prevents light from asource from impinging upon a photodetector. Rotation of the sensingelement momentarily displaces the opaque element, thereby permittinglight to fall upon the photodetector, thus producing an output signalwhich is utilized to stop movement of the paper until a printingoperation is completed.

9 Claims, 3 Drawing Figures PR/NT f/EAD SHEET PATENTEDJUH 10 ms QwmDEVICE FOR POSITIONING STOCK IN A PRINTING MECHANISM BACKGROUND OF THEINVENTION There are many printing operations in which printing takesplace on a continuous roll of stock to formlahels containing eitherbinary coded or alphanumeric information. In such systems the roll ofstock is pulled past the printing mechanism and stopped so that theprinting operation takes place at the desired area on the stock andsharp clear printing obtained. After the printing operation is finished,movement of the paper stock past the printing mechanism is resumed andthe printed material removed while a succeeding area of the rolled stockis positioned under the printing mechanism so the next label can beprinted. Because there are specific areas on the paper stock where theprinting is to occur, it is necessary to affect the stoppage of thepaper stock such that the printing areas are accurately positioned withrespect to the printing mechanism.

Because of the necessity of the accurate stoppage of the paper stock,various types of devices have been constructed to sense the movement ofthe paper. One such device includes a small wheel, the rotational rateof which is directly proportional to the linear motion of the paperstock. These devices can be satisfactory for some purposes. However, ifthe wheel slips with respect to the paper, inaccurate positioning of thepaper results.

Another type of prior art device consists of a photodetector elementpositioned on one side of the paper. A light source is positioned on theother side of the paper so that the light shines through the paper andis detected by the photodetector. Opaque marks are spaced along thepaper with the spacing representing the desired length of paper betweenprinting areas. The opaque marks block the light indicating that aparticular length of paper has passed through the printing mechanism.Blockage of the light results in the generation of a stop signal so thatthe area of the paper where printing is to take place is positioned withrespect to the printing mechanism. These systems are not fully adequatebecause variations in the thickness of the paper and slight wobbling ofthe paper can cause erroneous blockage of the light resulting ininaccurate stoppage of the paper.

SUMMARY OF THE INVENTION The invention is directed to a mechanism forcausing the stoppage of a roll of paper at accurate positions so thatprinting upon the paper can be effected at a specified area on thepaper. The preferred embodiment is described with respect to controllingthe motion of paper in a printing mechanism. It should be understoodthat the invention can be used to control the motion of any stock inother types of mechanism. Thus, the invention can also be used, forexample, to control sheet metal on a shear, plastic in a punch, etc. Inthe first preferred embodiment contemplated by the invention the paperstock is in the form of a continuous roll of backing carrying a seriesof equally spaced labels upon which the printing will occur. After theprinting operation, the labels can be peeled from the backing; andbecause of an adhesive on the backing of the labels, they can be appliedto any object the labels are intended to identify. The inventivemechanism is arranged to detect the edge of a label and to generate asignal coincident with the detection. The signal is used to stop themotion of the paper stock so that a label is properly positioned withrespect to the printing mechanism. After the printing operation iscompleted, motion of the rolled material is resumed until the next labeledge is detected to again stop the paper so that another label ispositioned for printing.

In an alternative preferred embodiment of the invention, the printingcan occur directly upon the rolled material so that no label edges areavailable for detection. In the alternative embodiment, performationsare placed at selected positions along the roll of material and thesensing element senses the edges of the perforations thereby effectingthe generation of the stop signal.

The inventive sensing device includes a rotatably mounted element whichslides along the paper stock during passage through the printingmechanism. When the sliding sensing element comes into contact with theedge of a label, the sensing element rotates causing the generation ofthe stop signal. Because in normal operation the sensing element slidesalong the stock, the slippage problem found in prior art systemsutilizing rotating elements is eliminated. This constitutes a markedadvance over the prior art systems in which the rotation of the sensingelement is intended to be directly proportional to the linear motion ofthe stock, because in such systems slippage of the sensing elementresults in inaccurate stoppage of the paper.

The rotational axes of the sliding element is coincidence with thelongitudinal axis of a shaft, one end of which is connected to a pivotpoint. When the sliding element contacts either the edge of a label or aperforation in the stock, the sliding element rotates, therebydisplacing the shaft about the pivot point. Rigidly attached to theshaft is an opaque member which is angularly disposed with respect tothe shaft. When the sliding member rotates, thereby displacing theshaft, the opaque member also is displaced in space. During the slidingof the element, the opaque member is in its normal position and isdisposed between a light source and a photodetector so that light cannotimpinge upon the detector. Upon rotation of the sliding element becauseof contact with the edge of a label, the displacement of the opaquemember allows light to impinge upon the photodetector resulting in thegeneration of a stop signal which is used to stop the movement of thepaper stock through the printing mechanism. The area, or position, ofthe paper upon which printing is intended to occur is thus located underthe printing mechanism. After printing is completed, motion of the stockis resumed until the sliding element contacts the next edge, therebyrepeating the process.

CROSS REFERENCE TO RELATED APPLICATION The printing mechanismschematically illustrated herein can be of the type described inapplication Ser. No. 418,722 filed Nov. 23, 1973 now US. Pat. No.3,848,257, by James R. Moss entitled Device for Printing Coded Labelsand the Like, and also assigned to the assignee of the instantapplication.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side view of a preferredembodiment of the instant invention.

FIG. 2 is a top view of the preferred embodiment shown in FIG. 1.

FIG. 3 is a preferred embodiment of exemplary control circuitry whichcan be used with the instant inventlOl].

DETAILED DESCRIPTION As shown in FIG. 1, the invention includes a Roller12 supporting a supply of Stock 11 upon which printing will occur.Roller 12 is rotatably mounted about its longitudinal axis so that theStock unrolls as a pulling force is applied thereto. The Stock passesover an Idler Roller 13 which is used to guide the Stock into ahorizontal position for feeding through the printing mechanism. Afterpassing through the printing mechanism. the Stock passes over anotherIdler Roller 14 and then to a Take-up Roller 16. A driving mechanism.such as a stepping motor. is coupled to Roller 16 to cause rotationthereof and thereby causes the Stock material to be pulled through theprinting mechanism. This technique of passing paper through varioustypes of mechanisms is well known to those skilled in the art and.accordingly, additional detail is not required herein.

The Stock upon which printing will occur consists of a Backing 17 uponwhich a plurality of Labels 18 have previously been applied. The Labels18 have an adhesive on the back thereof so that they cling to theBacking 17. After printing occurs. the Labels are removed from theBacking and are then capable of being adhesively applied to an articleto be identified by the printed label.

The invention consists of a generally square Slider Element 19 rotatablysupported about its axis of symmetry on a Shaft 21. Shaft 21 ispivotally attached to a fixed Pivot Point 22. Accordingly, Shaft 21 isfree to pivot about the Pivot Point 22 and Slider Element 19 is free torotate about the Shaft 21.

Fixedly attached to Shaft 21 is an Opaque Element 23. Because Element 23is fixedly attached to Shaft 21, rotation of Shaft 21 about Pivot Point22 results in the physical displacement of Element 23 in the mannerindicated by dotted lines.

As best seen in FIG. 2, Opaque Element 23 extends between a Light Source24 and a Photodetector 26. Because Element 23 is opaque, light cannotpass from Source 24 to Detector 26 when Opaque Element 23 is in theposition assumed when Sensing Element 19 is in the first slidingposition illustrated by solid lines in FIG. 1. However, when SliderElement 19 rotates because of contact with the edge of a Label 18, in amanner described hereinafter. Opaque Element 23 is displaced from thenormal position and permits light to impinge upon Photodetector 26.Photodetector 26 then provides a signal on Line 28. This signal is usedas a stop signal to actuate Control Circuitry 27 in a manner describedhereinafter. Obviously, if desired. the displacement of Opaque Element23 can be used to break an otherwise continuous illumination ofPhotodetector 26 by Source 24. The output signal on Line 29 of ControlCircuitry 27 controls the motion of the Stock through the mechanism.thereby permitting the accurate stopping of Labels 18 at the desiredlocations in response to the detection of the leading edges of theLabels.

Referring again to FIG. 1, the invention is utilized to detect thepresence ofa Label 18 so that the motion of the Stock through theprinting mechanism is stopped at a time when a Label 18 is locatedbeneath the Printing Head 32 and over the Printing Surface 33. Upon thecomplete stoppage of the motion. the Printing Head 32 prints on theLabel. and after the printing operation is completed. provides a signalto Control Circuitry 27 so that the motion of the paper is resumed untilthe next succeeding Label is properly located under the Printing Head.

FIG. 1 also shows a preferred embodiment of the configuration andarrangement of the Label Detecting Mechanism. The Slider Element 19 isgenerally square in configuration and therefore contains four sharpCorners 31. It should be noted, however. that the square configurationof Slider 19 is not essential as triangular. or hexagonal and otherpolygonal configurations can be utilized. the primary considerationsbeing the presence of sharp edges in the vicinity of the Corners 31 ofthe Slider Element and the symmetry about the rotational axis 21. TheSensing Element is mounted to rotate about the axis of symmetry. whichalso can be defined as'the intersection of the diagonals of the polygon.Sensing Element 19 also is provided with Concave Areas 34 on each sidethereof. Because of the presence of the Concave Areas 34, slight wavesor fluctuations in the paper which can be caused by insufficient papertension or variations in paper thickness will flow into the ConcaveAreas thereby rendering the system insensitive to such variations andimproving the accuracy of the system.

Positioned between the Sharp Edges 31 and Concave Areas 34 of SensingElement 19 are Flat Areas 36. In normal operation two of the Areas 36will slide along the moving Stock so that Opaque Element 23 remainsinterposed between Light Source 24 and Photodetector 26. The spanbetween successive Sharp Edges 31 exceeds the Spacing 37 between twoLabels. For this reason when the first Flat Area 36 leaves contact withthe Label and falls between two Labels. the Slider Element 19 is on avery slight angle and assists in causing Ele ment 19 to rotate. When theFlat surface 36 contacts the edge of a Label. the Sharp Edge 31 andSurface 36 prevent Sensing Element 19 from sliding onto the Labe]; thiscauses Slider Element 19 to rotate into the position indicated in dottedlines on FIG. 1. This rotation causes Opaque Element 23 to rise aboveLight source 24, thereby permitting light to impinge upon Photodetector26, thus providing a stop signal for the printing mechanism.Accordingly, Print Head 32 is positioned at a known location from theSlider Element 19 so that a Label is available directly under the PrintHead 32 when the stop signal is provided.

As Sensing Element 19 and the edge ofa Label come into contact, theLabel pushes against one of the Flat Surfaces 36 causing rotation in thecounterclockwise direction for the example shown. Rotation continuesuntil Element 19 is in the position shown in dotted lines, at which timethe Label has passed under Element 19. Accordingly. Element 19 dragsalong the surface of the Label. Friction between Slider Element 19 andthe Label 18 causes rotation to continue until the Sensing Element 19returns to its normally flat position under the assistance of a Spring25. Return of Element 19 to the normal position also results in OpaqueElement 23 returning to the normal position to again break the lightextending from Source 24 to Photodetector 26. The Sensing Element 19then continues to slide along the Label until contact with the edge ofthe next Label is made to generate another stop signal upon the nextrotation of Sensing Element 19.

If desired. Slider 19 can be used to detect perforations in the Stock.rather than the edges of the Labels. In this usage the total width ofSlider will exceed the width of the perforations to prevent the Sliderfrom extending into the perforations. Protrusions on theSlider 24 willbe slightly narrower than the perforations and will carry the sharpedges. Accordingly. the protrusions will slide along the stock betweenperforations and will catch the edge of the perforations to effectrotation of Slider 19. However. because the width of Slider 19 exceedsthe width of the perforations. Slider 19 is prevented from extendinginto the perforations and either tearing or binding the Stock.

FIG. 3 shows an exemplary type of Control Circuit which can be used withthe invention. The stop signal on Line 28 of Photodetector 26 is appliedto a Flip- Flop 38. Ordinarily. no signal will be present, and theoutput of Flip-flop 38 available on Line 42 will thus be a logic ONEcondition. This is applied as an input to AND Gate 39 which receivesanother logic ONE input from Printer 32. The input from Printer 32 onLine 41 will be a logic ONE in the instances when printing is not takingplace within the printer. Thus. with both input Terminals 41 and 42 ofAND Gate 39 at the logic ONE condition, the signal available on outputLine 29, which is the output line of Control Circuitry 27, is a logicONE; in this condition. the stock moves through the printer.

When a stop signal is applied to Line 28 of Flip-Flop 38, the FlipFlopchanges states so that the input on Line 42 of AND Gate 39 is a logicZERO. thereby changing the logic ONE condition on output Line 29 tologic ZERO. This causes the movement of the stock through the printingmechanism to stop. The logic ONE input on Line 28 is also applied to thePrinter 32 over Line 43 so that printing begins. When printing begins,the signal on Line 41 becomes a logic ZERO. The logic ONE condition onLine 28 is retained for only the short period of time during whichOpaque Element 23 is displaced from the normal position in which itinterrupts the light between Source 24 and 26. As soon as the normalinterrupting position is returned, the input on Line 42 returns to logicONE. However, because the input on Line 41 is now a logic ZERO. thelogic ZERO condition of output Line 29 remains. This condition continuesuntil Printer Mechanism 32 generates a signal indicating that theprinting operation has been completed, at which time a logic ONE isagain available on Line 41 and AND Gate 39 is again enabled andresumption of motion of the paper through the mechanism is affected. Itshould be noted that the actual control circuitry used with theinventive system can vary substantially within the purview of thoseskilled in the art dependent upon the exact control functions which aredesired for the stock upon which printing is made.

1 claim:

1. A device for sensing and positioning stock in a feed mechanism, saidstock including edges spaced at selected positions to define positionsat which an operation will occur in said feed mechanism comprising:

a sensing element arranged to slide along said stock and positioned tocontact said edges, said sensing 6 element having sharp portions in thevicinity of said contact so that said sharp portions contact said edges;

shaft means, said sensing element being rotatably 'mounted on said shaftmeans, said shaft means being pivotably mounted with respect to a fixedpoint;

light opaque fixedly coupled to said shaft means;

light source means and light detection means. said light opaque meansbeing normally interposed with said light source means and said lightdetection means; said sensing element being symmetrically configuredabout the point of rotation with respect to said shaft and beingconfigured so that rotation of said sensing element displaces saidopaque element and permits light from said light source to impinge uponsaid light detector. 2. The device of claim 1 wherein said sensingelement is a multisided polygon and said sharp portions are located atthe intersections of said sides of said polygon. 3. The device ofclaim 2wherein said sensing element further includes concave areas partiallyextending across said sides of said polygon.

4. The device of claim 2 wherein said polygon is four sided.

5. The device of claim 3 wherein said polygon is four sided.

6.1n a system for printing labels present on a continuous backing, saidpacking being pulled from a supply roller to a storage roller past aprinting mechanism. a device for accurately positioning said labels inthe proximity of said printing mechanism comprising:

means for sensing the edges of said labels as said labels travel towardsaid printing mechanism. said means for sensing having a point ofsymmetry and being configured to slide along said backing. said meansfor sensing having a plurality of sharp corners symmetrically disposedabout said point of symmetry;

means for rotatably supporting said means for sensing at said point ofsymmetry, said means for supporting being pivotably mounted with respectto a fixed pivot point;

light means, light detection means situated in the proximity of saidlight means; light opaque means interposed said light means and saidlight detection means, said opaque means being fixedly coupled to saidmeans for supporting;

said means for sensing being configured so that contact of said cornerswith the edges of said labels rotates said means for sensing to displacesaid point of symmetry and move said opaque means permitting light fromsaid source to impinge upon said detection means.

7. The system of claim 6 wherein said sensing element is a multisidedpolygon and said sharp corners are located at the intersections of thesides of said polygon.

8. The system of claim 7 wherein said sensing element further includesconcave areas partially extending across the sides of said polygon.

9. The system of claim 8 wherein said polygon is four sided.

1. A device for sensing and positioning stock in a feed mechanism, saidstock including edges spaced at selected positions to define positionsat which an operation will occur in said feed mechanism comprising: asensing element arranged to slide along said stock and positioned tocontact said edges, said sensing element having sharp portions in thevicinity of said contact so that said sharp portions contact said edges;shaft means, said sensing element being rotatably mounted on said shaftmeans, said shaft means being pivotably mounted with respect to a fixedpoint; light opaque fixedly coupled to said shaft means; light sourcemeans and light detection means, said light opaque means being normallyinterposed with said light source means and said light detection means;said sensing element being symmetrically configured about the point ofrotation with respect to said shaft and being configured so thatrotation of said sensing element displaces said opaque element andpermits light from said light source to impinge upon said lightdetector.
 2. The device of claim 1 wherein said sensing element is amultisided polygon and said sharp portions are located at theintersections of said sides of said polygon.
 3. The device of claim 2wherein said sensing element further includEs concave areas partiallyextending across said sides of said polygon.
 4. The device of claim 2wherein said polygon is four sided.
 5. The device of claim 3 whereinsaid polygon is four sided.
 6. In a system for printing labels presenton a continuous backing, said packing being pulled from a supply rollerto a storage roller past a printing mechanism, a device for accuratelypositioning said labels in the proximity of said printing mechanismcomprising: means for sensing the edges of said labels as said labelstravel toward said printing mechanism, said means for sensing having apoint of symmetry and being configured to slide along said backing, saidmeans for sensing having a plurality of sharp corners symmetricallydisposed about said point of symmetry; means for rotatably supportingsaid means for sensing at said point of symmetry, said means forsupporting being pivotably mounted with respect to a fixed pivot point;light means, light detection means situated in the proximity of saidlight means; light opaque means interposed said light means and saidlight detection means, said opaque means being fixedly coupled to saidmeans for supporting; said means for sensing being configured so thatcontact of said corners with the edges of said labels rotates said meansfor sensing to displace said point of symmetry and move said opaquemeans permitting light from said source to impinge upon said detectionmeans.
 7. The system of claim 6 wherein said sensing element is amultisided polygon and said sharp corners are located at theintersections of the sides of said polygon.
 8. The system of claim 7wherein said sensing element further includes concave areas partiallyextending across the sides of said polygon.
 9. The system of claim 8wherein said polygon is four sided.